7. PROJECT SUMMARY / ABSTRACT As access to antiretroviral therapy (ART) has expanded and people live longer with HIV, HCV mortality has increased. The burden is particularly high in people who inject drugs (PWID). However, HCV can be cured with highly efficacious medications resulting in calls for microelimination. In settings with key population-focused HIV epidemics, microelimination may be achieved by integrating HCV services with existing HIV and harm reduction services to simultaneously improve HIV and HCV outcomes. Our team has successfully scaled integrated care centers (ICCs) for PWID across India. ICCs provide vertically integrated, HIV prevention and treatment services in stand-alone stigma-free venues. We integrated HCV point-of-care testing in 2015 and demonstrated significant improvements in HCV testing and awareness. However, HCV treatment remains a missing component. Accordingly, we investigate the impact of the integration of HCV treatment with individually tailored treatment support into 7 PWID focused ICCs. Our Aims are to: Aim 1: Evaluate whether individual treatment outcomes in HCV mono- and HIV/HCV co-infected PWID can be optimized by tailoring treatment support in 7 PWID-focused integrated HIV/HCV prevention/treatment centers. Subaim 1A: Compare sustained virologic response (SVR) in PWID undergoing DAA-based HCV therapy randomized by a ?precision clinical trial? approach to varying levels (low, medium, high) of treatment support tailored to need using an algorithm based on factors associated with early HIV viral suppression. Subaim 1B: Estimate the incidence of HCV- reinfection by HIV status among PWID achieving SVR. Subaim 1C: Evaluate the impact of HCV cure on HIV viral suppression among HIV/HCV co-infected PWID. Aim 2: Characterize barriers and facilitators to integration of HCV treatment with tailored treatment support and HIV services through a mixed-methods evaluation to facilitate implementation in other settings. Aim 3: Estimate population-level effectiveness and cost-effectiveness of integrating HCV testing and treatment with essential HIV prevention and treatment services. Subaim 3A: Assess the observed and future impact of integrated HCV/HIV testing and treatment on chronic HCV and HIV prevalence and incidence among PWID using epidemic modeling and serosurvey data. Subaim 3B: Evaluate the cost-effectiveness of integrated HCV/HIV testing and treatment and identify the most cost-effective HCV treatment support strategies. To achieve these aims, we will scale on-site HCV testing and treatment in 7 ICCs across India that already deliver essential HIV services to ~10,000 PWID. Treatment support will be personalized using an algorithm based on early HIV viral suppression to triage clients into two strata: minimal and elevated risk for failure. Using a novel unbalanced randomization approach, we will assess efficacy of low (self-administered), medium (peer navigator) and high intensity (DOT) treatment support strategies within strata of treatment failure risk and overall. Population outcomes including reduced transmission will be evaluated through cross-sectional surveys, epidemic and cost-effectiveness modeling.